Integrated Scenarios of Climate, Hydrology, and Vegetation for the Northwest

Climate change impacts are expected to vary greatly from place to place. For this reason, regionally specific climate projections are critical to help farmers, foresters, city planners, public utility providers, fish and wildlife managers, and others plan how best to manage resources in their parts of the world.

In the Northwest, temperatures will likely increase 2-15 degrees Fahrenheit by 2100. The region’s winters are expected to become wetter, and summers may be drier. Snowpack will likely decrease substantially, and snowmelt run off may occur earlier in the year. Forest types are expected to change from maritime evergreen forests to subtropical mixed-woodland forests. And wildfires will most likely become more frequent and severe over the next several decades.

Climate scientists from around the world collaborate regularly to produce global climate model simulations, the most recent of these being the World Climate Research Programme’s fifth phase of the Coupled Model Intercomparison Project (CMIP5).

CMIP5 represents a collaborative effort of more than 20 climate modeling groups from around the world, using the same experimental setup, to provide the best available climate modeling. While CMIP5 makes possible many targeted studies of climate change, it does not provide the degree of resolution necessary to generate meaningful projections about likely climate changes for a given region. For example, CMIP5 does not distinguish the Cascade Mountains from the Willamette Valley, two parts of the Northwest that will likely see different climate impacts in future decades. Scientists must translate, or “downscale”, climate data from CMIP5 to create impact models for things like forest and range dynamics, crop growth, and seasonal patterns of water availability.

The goal of the Integrated Scenarios of Climate, Hydrology, and Vegetation for the Northwest project was to use the global climate models from CMIP5 to describe as accurately as possible what the latest science says about the Northwest’s future climate. Researchers started the Integrated Scenarios project by evaluating the ability of CMIP5 models to simulate observed patterns in the Northwest region. The researchers then used the best of these models to project likely future changes to Northwest’s climate, hydrology, and vegetation. Later the Southeast Climate Science Center (http://www.doi.gov/csc/southeast/index.cfm) supported a relatively small amount of additional work for the project’s Principal Investigators so that CMIP5 models could also be downscaled for all other regions across the greater continental United States.

The Integrated Scenarios project has produced a series of datasets, now available online, that can be used to address specific management questions. These datasets are compatible with other hydrological and ecological modeling efforts and represent a next-generation climate change framework for resource managers. This framework supports a range of management activities to increase the resilience of Northwest ecosystems, agricultural systems, and built environments. It allows the development of tools to help resource managers identify the most vulnerable areas in the region and to develop strategies for reducing the impacts of climate change. For example, the datasets might be used to help project the number of frost-free days and minimum average temperatures in future winters. These variables can help managers understand likely implications of global warming on outbreaks of pests like the mountain pine beetle that are regularly killed by freezing temperatures.

On April 17, 2014, results from the Integrated Scenarios project were presented at a daylong workshop in Portland, Oregon. The U.S. Fish and Wildlife Service has made video from the workshop available. The video can be accessed here:

Climate change is expected to have different effects in different parts of the world. For this reason, regionally-specific projections of climate and environmental change are important to help those who want to plan how best to adapt. The goal of this project was to use the latest global climate models and state of the science models of vegetation and hydrology, to describe what the latest science says about the Northwest’s future climate, vegetation, and hydrology. Researchers in the project began by evaluating the ability of climate models to simulate observed climate patterns in the Northwest region. The best-performing models were ‘downscaled’, that is, remapped onto the finer grids used in models of hydrology and vegetation. The researchers used the best performing models to project likely future changes to the Northwest’s climate, hydrology, and vegetation. One product of this work is a series of freely available datasets that can be used to address specific management questions. These datasets are compatible with other hydrological and ecological modeling efforts and represent a next-generation climate change framework for land managers. This framework supports a range of management activities to increase the resilience of Northwest ecosystems, agricultural systems, and built environments. It allows the development of tools to help land managers identify the most vulnerable areas in the region and to develop strategies for reducing the impacts of climate change.

This project was funded jointly by the Department of the Interior’s Northwest Climate Science Center and by the National Atmospheric and Oceanic Administration’s Climate Impacts Research Consortium. To learn more about the project visit the Integrated Scenarios website or contact Phil Mote at pmote@coas.oregonstate.edu.

Prioritize projects to increase resilience of forests and grasslands: The Integrated Scenarios datasets can help managers identify potentially vulnerable areas and prioritize investments in these areas to increase the resilience of forests and grasslands.

Projected changes to vegetation in response to fire: This project provides projected changes in vegetation in response to increased fire severity, frequency, and extent, which managers can factor into land management plans.